Hantaviruses cause severe diseases in humans: hemorrhagic fever with renal syndrome (HFRS) and Hantavirus cardiopulmonary syndrome (HCPS). The lack of vaccines or specific drugs to prevent or treat HCPS, and the requirement for conducting experiments in a biosafety level 3 laboratory (BSL-3) limit the ability to probe the mechanism of infection and disease pathogenesis. Case fatality ratios generally range from 30 to 50%. No vaccines or specific therapy are currently available for use in the US. The high case-fatality rate, the absence of vaccines and therapeutics, and the ability of Hantaviruses to be transmitted via the aerosol route have led to their categorization as Category A pathogens, and potential agents of biological warfare. We therefore initiated a program to study Sin Nombre virus (SNV) killed with a calibrated dose of UV radiation as a model system to dissect its mechanism of cellular entry in BSL-2 facilities. We demonstrated that UV-killed SNV attaches to the glycosylphosphatidylinositol (GPI)-anchored protein decay accelerating factor (DAF/CD55) and low affinity state avb3 integrins in a manner that parallels live virions. We propose to screen for small molecule inhibitors of hantavirus infection by blocking the binding of hantaviruses to their surface co- receptor DAF and cellular entry through ?v?? integrins. To achieve these goals, we will pursue the following aims: Aim 1. To develop HTS primary screens for small molecule inhibitors of binding of Sin Nombre Viruses to DAF and ?v??. Aim 2. To develop secondary HT screening assays for small molecule inhibitors of SNV cell interactions. PUBLIC HEALTH RELEVANCE: The proposed work uses a unique interdisciplinary combination of virology and quantitative biophysical tools to identify small molecule inhibitors of pathogenic hantaviruses, which cause hantavirus cardiopulmonary syndrome (HCPS) and hemorrhagic fever with renal syndrome (HFRS). There are currently no vaccines or specific therapy that are available for use in the US to treat HCPS or HFRS. The high case-fatality rate, the absence of vaccines and therapeutics has led to their categorization as Category A pathogens, and potential agents of biological warfare. Our preliminary studies have shown that UV-killed viruses bind to the same receptors used by live viruses. Thus we will develop flow cytometry-compatible high throughput screening assays for small molecule inhibitors of the binding of hantaviruses to its surface co-receptor Decay Accelerating factor and entry receptor ?v?? integrin. Successful completion of this project will lead to the development of therapeutic intervention-probes for hantavirus infection and other pathogens that rely on these receptors for infection.